Here is an article that shows comparison screenies between Crysis, COD4, UT3...
Call of Duty 4 vs. Crysis
http://www.pcgames.de/aid,617154/News/Crysis_vs_CoD_4_-_Explosive_Vergleichsbilder/
Far Cry 2 vs. Crysis
http://www.pcgames.de/aid,610803/Ein_Ausflug_nach_Afrika_-_Erste_Vergleichsbilder_zu_Far_Cry_2/
Unreal Tournament 3 vs. Crysis (Part One and Part Two)
http://www.pcgames.de/aid,602757/CryEngine_2_vs_UnrealEngine_3_-_Sieben_neue_Vergleichsbilder/
http://www.pcgames.de/aid,607201/CryEngine_2_vs_UnrealEngine_3_-_Acht_neue_Vergleichsbilder/
There are many more comparisons just browse inside, in my opinion I think every game has its strengths when comparing, Crysis pawns in terms of photo realsim, UT3 in terms of design and texturing, COD4 can be compared to crysis, however, it lacks some of crysis features like Crysis has more destructibility intensity...
I also like this comparison, explosions:
http://www.pcgames.de/?menu=browser&article_id=617154&image_id=713784
Overall, I think COD4 doesn't look that bad afterall, demo was awesome and I'm really looking forward to it as crysis, of course UT3 and others
